The present invention relates to an injection apparatus particularly suitable for injecting starting fluid into the cylinders of an internal combustion engine, and more particularly to such an apparatus operated by the on-board compressed air system of a motor vehicle.
An internal combustion engine can be started more quickly and easily if a charge of starting fluid, such as ether, or preferably a combination of ether and a lubricant, is injected into the cylinders along with the regular fuel supply. Various devices have been attached to engines that provide a pressurized supply of starting fluid and a valve that permits a charge to be injected at the appropriate time. Some such devices simply allow the valve to be operated manually at will by a remote cable control. A more sophisticated device, described in this inventor's U.S. Pat. No. 3,620,424, issued on Nov. 16, 1971, provides for automatic injection of a predetermined quantity of starting fluid when the engine's starter motor is operated.
The automatic injector referred to above utilizes a solenoid to operate two valves in sequence whenever the starter motor is energized. A first valve permits starting fluid to escape from a pressurized tank or reservoir into a resilient metering chamber. When the injector is actuated, a second valve permits the predetermined quantity of fluid contained by the metering chamber to be expelled through a starting fluid delivery conduit into the engine. This device insures that a measured quantity of starting fluid is injected each time the engine is started. Since its operation is automatic, it can prevent the injection of starting fluid after the engine has been warmed up, thereby avoiding engine damage that could otherwise result.
Starting fluid injectors have proven particularly suitable for use with large diesel-powered vehicles since a diesel engine is not started and self-sustaining until it is able to maintain the minimum internal temperature required to cause combustion upon compression of the air-fuel mixture. Engines equipped with compressed air-operated starter motors must reach this minimum starting temperature before their reserve of compressed air is exhausted if the expense and time loss of bringing a large portable compressor to the vehicle is to be avoided. If an electrically powered starter is used, similar limitations are imposed by the amount of energy available from the vehicle's battery.
When there is doubt about the ability to restart an engine, it must be left to idle, consuming expensive fuel and contributing to air pollution. It is therefore highly desirable to simplify the starting fluid injecting mechanism and to increase its reliability.